The GPUS was founded in 2001 as the evolution of the Association of State Green Parties (ASGP), which was formed in 1996.[8] After its founding, the GPUS soon became the primary national green organization in the country, eclipsing the Greens/Green Party USA (G/GPUSA), which formed in 1991 out of the Green Committees of Correspondence (CoC), a collection of local green groups active since 1984.[9] The ASGP had increasingly distanced itself from the G/GPUSA in the late 1990s.[10]

The GPUS has had several members elected into state legislatures, including in California, Maine and Arkansas. In September 2017, independent Ralph Chapman, member of the Maine House of Representatives, switched his affiliation to the Green Party.[14] A number of Greens around the United States hold positions on the municipal level, including on school boards, city councils and as mayors.

The political movement that began in 1985 as the decentralized Committees of Correspondence[15] evolved into a more centralized structure by 1990, opening a national clearinghouse and forming governing bodies, bylaws and a platform as the Green Committees of Correspondence (GCoC) and by 1990 simply The Greens. The organization conducted grassroots organizing efforts, educational activities and electoral campaigns.

Internal divisions arose between members who saw electoral politics as ultimately corrupting and supported the notion of an "anti-party party" formed by Petra Kelly and other leaders of the Greens in Germany[16] vs. those who saw electoral strategies as a crucial engine of social change. A struggle for the direction of the organization culminated a "compromise agreement", ratified in 1990 at the Greens National Congress in Elkins, West Virginia and in which both strategies would be accommodated within the same 527 political organization renamed the Greens/Green Party USA (G/GPUSA). It was recognized by the FEC as a national political party in 1991.

The compromise agreement subsequently collapsed and two Green party organizations have co-existed in the United States since. The Green Politics Network was organized in 1990 and the National Association of Statewide Green Parties formed by 1994. Divisions between those pressing to break onto the national political stage and those aiming to grow roots at the local level continued to widen during the 1990s. The Association of State Green Parties (ASGP) encouraged and backed Nader's presidential runs in 1996 and 2000. By 2001, the push to separate electoral activity from the G/GPUSA issue-based organizing led to the Boston Proposal and subsequent rise of the Green Party of the United States. The G/GPUSA lost most of its affiliates in the following months and dropped its FEC national party status in 2005.

In 2016, Mark Salazar set a new record for a Green Party nominee for Congress. Running in the Arizona 8th district against incumbent Republican Congressman Trent Franks, Salazar received 93,954 votes or 31.43%.[17]

Peter Camejo was quoted in 2002 as claiming that he was a watermelon—green on the outside, but red on the inside.[19] In January 2004, he initiated the Avocado Declaration, which compares Greens to avocados. "An avocado is Green on the outside and Green on the inside".[20] The Declaration goes on to explain that Greens have a vital role in bringing democracy to the otherwise undemocratic two party system of the United States; that the Greens have a unique and independent identity as a third party, which cannot be subsumed into the Republican or Democratic parties; and that they cannot be dismissed by Republican or Democratic critics by implying that they are merely socialists or communists.

The Green Party does not accept donations from corporations, political action committees (PACs), 527(c) organizations or soft money. The party's platforms and rhetoric harshly criticize corporate influence and control over government, media and society at large.[21]

The Green Party calls for proving tuition-free college at public universities and vocational schools, increasing funding for after-school and daycare programs, cancelling all student loan debt, and repealing the No Child Left Behind Act. They are strongly against the dissolution of public schools and the privatization of education.[23]

The GNC is composed of delegates elected by affiliated state parties. The state parties also appoint delegates to serve on the various standing committees of the GNC. The National Committee elects a steering committee of seven co-chairs, a secretary and a treasurer to oversee daily operations. The National Committee performs most of its business online, but it also holds an annual national meeting to conduct business in person.

The Green Party has its strongest popular support on the Pacific Coast, Upper Great Lakes, and Northeast, as reflected in the geographical distribution of Green candidates elected.[37] As of June 2007[update], Californians have elected 55 of the 226 office-holding Greens nationwide. Other states with high numbers of Green elected officials include Pennsylvania (31), Wisconsin (23), Massachusetts (18) and Maine (17). Maine has the highest per capita number of Green elected officials in the country and the largest Green registration percentage with more than 29,273 Greens comprising 2.95% of the electorate as of November 2006[update].[38]Madison, Wisconsin is the city with the most Green elected officials (8), followed by Portland, Maine (7).

The 2016 presidential campaign of Jill Stein got substantive support from counties and precincts with a high percentage of Native American population. For instance, in Sioux County (North Dakota, 84,1% Native American), Stein gained her best county-wide result: 10.4% of the votes. In Rolette County (also North Dakota, 77% Native American), she got 4.7% of the votes. Other majority Native American counties where Stein did above state average are Menominee (WI), Roosevelt (MN) and several precincts in Alaska.[39][40]

In 2005, the Green Party had 305,000 registered members in states allowing party registration and tens of thousands of members and contributors in the rest of the country.[41] One challenge that the Green Party (as well as other third parties) faces is the difficulty of overcoming ballot access laws in many states.

As of October 2016[update], 143 officeholders in the United States were affiliated with the Green Party, the majority of them in California, several in Illinois, Connecticut, Maine, Massachusetts, Oregon, Pennsylvania, and Wisconsin, with five or fewer in ten other states.[44] These included one mayor and one deputy mayor and fourteen county or city commissioners (or equivalent). The remainder were members of school boards, clerks and other local administrative bodies and positions.[44]

On September 21, 2017, Ralph Chapman, a member of the Maine House of Representatives, switched his party registration from unaffiliated to Green, providing the Green Party with their first state-level representative since 2014.[14]Henry John Bear became a member of the Green Party in the same year as Chapman, giving the Maine Green Independent Party and GPUS its second currently-serving state representative, though Bear is a nonvoting tribal member of the Maine House of Representatives.

No nominee of the Green Party has been elected to office in the federal government.

In the early decades of Green organizing in the United States, the prevailing American system of money-dominated elections was universally rejected by Greens, so that some Greens were reluctant to have Greens participate in the election system at all because they deemed the campaign finance system inherently corrupt. Other Greens felt strongly that the Green Party should develop in the electoral arena and many of these Greens felt that adopting an alternative model of campaign finance, emphasizing self-imposed contribution limits, would present a wholesome and attractive contrast to the odious campaign finance practices of the money-dominated major parties.

Over the years, some state Green parties have come to place less emphasis on the principle of self-imposed limits than they did in the past. Nevertheless, it is safe to say that Green Party fundraising (for candidates' campaigns and for the party itself) still tends to rely on relatively small contributions and that Greens generally decry not only the rise of the Super PACs, but also the big-money system, which some Greens criticize as plutocracy.

Some Greens feel that the Green Party's position should be simply to follow the laws and regulations of campaign finance.[67] Other Greens argue that it would injure the Green Party not to practice a principled stand against the anti-democratic influence of money in the political process. Candidates for office, like Jill Stein, the 2012 and 2016 Green Party nominee for the President of the United States, typically rely on smaller donations to fund their campaigns.[68]